Rigid-prong self-opening binder



J. K. DUNCAN RIGID-PRONG SELF-OPENING BINDER Oct. 9, 1962 Filed Aug. e.195s 2 Sheets-Sheet 1 fZZ @X24 @E4 ZZ" Emmi;

frzec/ 90.729615 racer? 2 Sheets-Sheet 2 Filed Aug. 6, 1958 3,057,357RIGlD-PRQNG SELF-@PENING BNDER `'lames K. Duncan, Chicago, Ill.,assigner to Duncan Research, Chicago, Ill., a partnership Filed Aug. 6,1958, Ser. No. 753,548 7 Claims. (Cl. 129-24) My invention relates to animproved rigid-prong selfopening binder.

In notebooks, brochures, and loose leaf books it is necessary to bindfrom a few sheets of paper to a stack of papers perhaps 1" thick to forma unitary pamphlet or book. Preferably, the binding should be such as topermit the respective sheets to be laid at in opened position to permitthe user to read the same without holding the sheets back. Plasticbinders with large numbers of relatively flexible iingers have been usedfor this purpose. These, however, require the use of special machines toflex the many fingers to open position in unison and to permit theinsertion of the sheets. Removal or change of the sheets can also beaccomplished only with access to such special machines. Spiral wirebinders are likewise generally useful for pamphlets of this generaltype, but they too require special machinery to thread the spiral wirethro-ugh the openings in the sheets to form the completed pamphlet.

In accordance with the present invention an improved binder mechanism isprovided in which the sheets may be inserted and removed without the useof special machinery. At the same time, however, the pamphlet, whenformed, is a unitary object in which the sheets are held in assembledrelation and do not tend to pull free. In brief, the apparatus of thepresent invention is characterized by the use of prongs which arerelatively rigid and are not flexed to add or remove the sheets. Theprongs may be made relatively heavy to provide a booklet with only asmall number of holes in each page including, for example, conventionalthree and five hole pages. The prongs are carried by, and are preferablyformed in a unitary structure with, a pair of spaced complementaryrelatively movable elongated rockable members. These members arepermanently connected together by an intermediate or fulcrum member inthe form of a flexible membrane or hinge serving to hold them fromspreading while permitting them to assume either a position holding theprongs in closed position or a position holding the prongs in openedposition. Further in accordance with the present invention a movablespreader is located at the edges of the rockable members opposite thefulcrum member and prongs. This spreader in one position holds therockable members in the prong-opening position for the insertion,removal, or replacement of the sheets.

In accordance with one embodiment of the present invention, the fulcrummember is in the form of a ilexible diaphragm which is formed from aunitary plastic extrusion with the rockable members. Outboard thisdiaphragm member (on the side opposite the prongs) there is provided aspreader member that is slideably positioned in the unit. This spreadermember is a relatively rigid plastic extrusion having outboard andinboard surfaces that slide respectively inside and outside the edges ofthe rockable members. With the prongs in the closed position, theoutboard sliding surfaces of the spreader member bear on the insidefaces of the rockable members to tension the web and provide leveraction urging the prongs to closed position. When the prongs are to beopened, the spreader member is withdrawn and reinserted in alternateposition Where the inboard surfaces bear on the outside edges of therocking members. It then holds together the edges of the rockablemembers opposite the prongs. At this time, the diaphragm is exed to anPatented Oct. 9, 1962 ICC arcuate conguration and the prongs are swungto opened position where the papers may be inserted or removed. Theoperation of moving the spreader from the prongclosing to theprong-opening position is merely one of slidably withdrawing the samefrom the prong-closing position (outboard surfaces bearing against therockable members) and sliding it back on in the prong-opening position(inboard surfaces bearing against the rockable members).

It is therefore a general object of the present invention to provide animproved self-opening binder using relatively rigid prongs.

Another object of the present invention is to provide an improvedself-opening binder using relatively rigid prongs that is particularlyadapted to manufacture fromy plastic materials in an inexpensive formsuitable for use by students, small business, and in other applicationswhere the complexity and expense of special opening and closingequipment cannot be tolerated.

Still another object of the present invention is to provide an improvedbinder mechanism that is especially adapted for manufacture by the useof plastic extrusion technique.

Yet another object of the present invention is to provide an improvedbinder in which all parts, including relatively rigid prongs, can bemade from an extrusion.

Yet another object of the present invention is to provide an improvedbinder mechanism in which a pair of relatively rigid prong-holdingrocking members are connected together by a movable web serving as afulcrurn and in which a spreader member serves in one position totension' the web and force the prongs to closed position and in anotherposition serves to iiex the web and open the prongs.

It is still another object of the present invention to provide a untiarybinding having a shiftable member which in one position forces theprongs to open position and holds them in that position and in anotherposition forces the prongs to closed position and holds them in thatposition.-

Further it is an'object of the present invention to provide a bindinghaving the foregoing objects and advantages and in which the sheets maybe laid flat in the opened position for use.

Further it is an object of the present invention to provide a bindinghaving the foregoing objects and advan-l tages Which has an essentiallyflat back side to permit the binding to be laid on its back with theprongs either in open or closed position to permit the sheets to bereadily inserted and removed with the back in such position and topermit the assembled brochure, pamphlet or book to be read with thepages laid flat.

Yet another object of the present invention is to provide an improvedrigid prong self-opening binder which includes conformations serving asstops to prevent undue flexure or bend.

Another object of the present invention is to provide a binder which canbe readily manufactured by plastic extrusion technique in conjunctionwith cam elements operative on the soft heated plastic to form thecooperating' prong portions.

Yet another object of the present invention is to provide an improvedrigid-prongbinder with readily removable prongs to accommodate paperhaving varying numbers of holes.

Still another object of the present invention is to provide an improvedrigid-prong binder using prong conformations that provide a high degreeof strength while at the same time aiding the insertion of sheets.

Still another object of the present invention is to provide an improvedself-contained binder that is characterized by resistance to breakage,resistance to changes in temperature and moisture, adapted for use withplastic materials having natural and attractive single or multiplecolors, is suitable for use in many sizes adapted for varying numbers ofpages and varying page dimensions, provides a back portion having aconvenient place for labels, is suitable for use with a small number offingers and hence only a small number of holes in the sheets of paper orin the alternative can be used with a large number of fingers and acorresponding large number of holes in the sheets, and incorporatesother features of construction combination and arrangement rendering thebinder especially suitable for practical low-cost application wherespecial binding machinery cannot be used.

The novel feautres which I believe to be characteristic of my inventionare set forth with particularity in the appended claims. My inventionitself, however, together with further objects and advantages thereof,Will best be understood by reference to the following description takenin conjunction with the accompanying drawings, in which:

FIGURE l is a top plan view of a completed booklet bound with a bindermechanism constructed in accordance with the present invention;

FIGURE 2 is an enlarged fragmentary end elevational view of the bookletof FIGURE 1;

FIGURE 3 is a greatly enlarged cross-sectional view through the axis 33, FIGURE l;

FIGURE 4 is a view like FIGURE 3 but showing the binder in the openedposition for the reception or removal of papers;

FIGURE 5 is a view like FIGURE 3 but of a modied form of the binder;

FIGURE 6 is an enlarged fragmentary view of FIG- URE 5;

FIGURE 7 is a View like FIGURE 5 but showing the binder in the openedposition for the reception or removal of papers;

FIGURES 8 and 9 are views like FIGURES 3 and 4, respectively, butshowing a further alternative embodiment of the present invention;

FIGURES l0 and ll are Views like FIGURE 3 but showing modification ofthe binders of FIGURES 3 and 8, respectively, suitable for manufacturefrom sheet metal; and

FIGURE l2 is a cross-sectional view through axis 12-12, FIGURE 11.

Referring now to FIGURE 1, the completed booklet there shown consists ofa binder portion shown generally at 20 and a booklet portion indicatedgenerally at 22. The latter consists of a stack of sheets of paper orthe like 22a, FIGURE 2, which are sandwiched between a pair of backingor cover sheets 22b, FIGURE 2. As hereafter described in detail, thebinder shown generally at 20', FIG- URES l and 2, defines a series ofrelatively rigid prongs 24 which pass through the registered holes 22ein the sheets and covers of the booklet portion to hold the sametogether and define a booklet.

The structure of the binder portion 20 is best seen in FIGURE 3. Itconsists of a pair of opposed complementary relatively rigid rockablemembers 26 and 28. A fulcrum member in the form of diaphragm 30` isformed integrally with and extends between these opposed rocking membersas shown. Each prong 24 is likewise formed integrally with the rockablemembers and extends from the rockable member 26 to the rockable member28, as shown. The prongs are severed or interrupted at 24a to form thecooperating short prong element or portion 24b and the long prongelement or portion 24e.

The spreader in the form of slide 32 is received on the inboard faces ofthe rockable members 26 and 28 to close the prongs, as in FIGURE 3. Inthe alternative this member fits over the outboard faces of thesemembers to open the prongs as in FIGURE 4. The spreader 32 has abackbone 32a which is relatively rigid and a pair of opposed angeportions 32b and 32C, respectively. As shown, the

outboard edges of the flanges 32b and 32C each have a longitudinalV-shaped groove or way, 132b and 132C, respectively. These ways receivedthe similarly shaped inboard V-shaped longitudinal ridges on the inboardfaces of the rockable members 26 and 28, respectively, these ridgesbeing indicated at 26a and 28a, FIGURES 3 and 4. On their inboard edges,the anges 32b and 32C each have a longitudinal ridge 23212` and 232C,respectively. These mate with and ride in the longitudinal V-shapedgrooves or ways, 26b and 28h, respectively, formed on the rockablemembers 26 and 28 as shown in FIGURE 4.

On its back or out-board side the backbone portion of the spreader 32has a pair of spaced overhanging portions 32d joined by a recessedportion to define the shallow groove 32e. A removable title card 34,which may be of paper or any other suitable material, is slidablydisposed within this groove and serves to bear the titleI of the bookletor other information as desired.

Preferably, a pair of caps 36 are located at the opposite ends of thebinder 20. Each of 4these may be of any construction well known to theart. In the form shown, they are formed of stamped sheet metal and haveoverhanging ears 36a, FIGURES 1 and 3, which frictionally grip the endsof the outboard faces of the rockable members 26 and 28 to provide anattractive end covering for the binder which may be readily removed topermit opening of the binder.

As shown in FIGURE 3, the binder 20 is in the closed position. In thiscondition, the flanges 32b and 32C of the spreader 32 bear outwardlyagainst the inside or inboard faces of the rockable members 26 and 28,respectively. The spreader 32 is held in this position by the ways 132band 132e which receive the ridges 26a and 28a of the rocking members 26and 28, respectively. This outward force is suflicient to bring theportions 24b and 24e -of the prongs 24 into engagement and to pull thediaphragm portion 30 into a taut position. It will be noted that thisaction is in the nature lof lever action with the taut diaphragm portion30 serving as a fulcrum to prevent spread of the rockable members andwith the ends of the rockable members 26 and 28 spaced in accordancewith the dimensions of the spreader 32, and with the ends of the prongportions 24b and 24C brought together in scissors action as shown.

The binder 20 is changed from the cl-osed position to the `open positionby sliding the spreader 32 out of the binder, pinching the free ends ofrockable members 26 and 28 together (by grasping them adjacent thegrooves 26b and 28b), and then reinserting the spreader 32 as shown inFIGURE 4. At this time the inboard ridges 232b land 232e 'of thespreader are received in the grooves 26b and 28b and the binder is heldin the position of FIGURE 4. At this time the spreader acts as a clamp.The rockable members 26 and 28 rock in relation to each other indirection to spread or open the relatively rigid prong portions 24b and24C as is shown in FIGURE 4. The fulcrum member '30 is flexed in thisaction and in offering resistance to the squeeze applied to Itherockable members fit serves in lever action to rock the rockable membersas shown and to open or spread the rigid prongs.

The lever act-ion of the spreader in the opened condition of FIGURE 4differs from that in the closed condition of FIGURE 3 in that thediaphragm portion 30 is under compression rather than tension, in thatthe ends of the rockable members 26 and 28 are held together rather thanspread apart, and in that the prongs 24b and 24C are not in engagementand exent no forces in the mechanical system.

As shown in FIGURES 1-4, the backing is made of plastic material. Anysuitable plastic may be employed. The fulcrum member 30 in the form of adiaphragm or web is made relatively thin and flexible. The spreader 32,the rockable members 26 and 28, and the prongs 24 are made relativelythick and inflexible. Vinyl plastics polystyrene, butyrate, andpolyethylene plastics are conapaiser sidered especially suitable for thebacking shown in these iigures because these materials in relativelythin sections display a high degree of flexibility and in fairly thicksections display suicient rigidity for the purposes of the binder.

Preferably, the binder is made from plastic extrusions. In the case ofslide 32, such construction involves no problems, since thecross-section along the length of this member is uniform. In the case:of the rockable members 26 and 28, diaphragm 30, and prongs 24, it iscontemplated by the present invention that extruded parts be initiallymade with the prongs 24a in the form of a continuous section having thecross-section of the prongs slightly opened. The soft plastic of thissection is turned in by passing the extrusion over suitable xed camelements, thus closing the prongs. After formation of this extrusion,the portions between the prongs 24 are removed by sawing or millingoperations to form the unit as seen in FIG- URES 1-3.

In FIGURE l0, the binder of FIGURES 1-4 is shown in a modiiied formsuitable for manufacture from sheet metal. Parts similar to those in thebinder of FIGURES 1-4 in this figure are indicated by like referencenumerals with the number 400 added. In the construction of FIG- URE 10,the relatively rigid rockable members 426 and 428 are defined by matingdouble thicknesses of the sheet metal of which the binder is made. Therelatively flexible diaphragm or web part 430 is defined by a singlethickness of the same sheet of metal. The prongs 424 are likewise formedof a single thickness of this metal, with the interruption 424a servingto define the two prong parts. In the unit of FIGURE 10, the spreader432 is similarly formed of sheet metal with iiange parts 432b and 432e,as shown. The title card 434 is received within the shallow slot yorgroove defined by the spreader 432, as shown.

In the prong closed position of FIGURE 10, the outboard faces of theflanges 432b and 432C of the spreader bar 432 bear against the inboardfaces of the free ends of the rockable members 426 and 428, as shown.This tensions the diaphragm part 430 and tends to flex it in thepnong-closing direction in the same lever actio-n as is above describedwith reference to FIGURE 3. The prongs are thus held closed.

To open the prongs, the spreader 432 is removed, the free ends of therockable members 426 and 428 are pinched together, and the spreader 432reinserted with its inside faces of the iianges 432b and 432e bearingagainst the outside faces of the rockable members 426 and 428. Thisholds the rockable members in the prong- Opening position similar tothat of FIGURE 4 and permits the insertion or removal `of the sheetsconstituting the booklet.

FIGURES 5-7 show another alternative form of the binder of FIGURES 1-4.In this form, the parts similar to those of FIGURES 1-4 are indicated bylike reference numerals with 500 added. As shown, the rockable members526 and 52S are for-med of a relatively thick section and define a pairof opposed grooves 526C and 528C. The spreader 532 fits in these groovesand in the inserted position of FIGURE 5 tends to spread the adjacentportions of the rockable members 526 and 528. This rocks the prong 524in the closing direction against the diaphragm 530 serving as a fulcrum.This serves to hold the prong in closed position.

The binder of FIGURES 5-7 is Shown in opened position at FIGURE 7. Thebinder is thus opened by pinching the free ends of the rockable members526 `and 528 together, thereby flexing the diaphragm portion 530 androcking the rockable members 526 and 528 in the prongopening direction.

The prongs of the binder of FIGURES 5 to 7 are interrupted only at theportion adjacent the top rockable member 526. These prongs are made ofprogressively decreasing cross-sectional area extending from their rootends 524C, FIGURE 5, to their tip ends 524d, FIGURE 5. This `serves toprovide maximum hook strength in the prongs for the `amount of materialemployed and in addition serves to facilitate the insertion and removalof the sheets by providing a relatively small prong area at the pointwhere the sheets must be laid over the prongs.

The binder of FIGURES 5 to 7 has a pair of relatively rigid heavingheavy covers which are indicated at 540 and 542, respectively. Thesehave flexible root portions at 540a and 542a, respectively, which freelyex as shown in FIGURE 7 to open the covers for use of the booklet andfor the insertion or removal of the sheets. The covers 540 and 542 aresecured in the rockable members 526 and 528 by inserting their ends inthe slots 526d and 528ml, as shown. Adhesive 541, FIGURE 6 is used forthis purpose.

The binder of FIGURES 5 to 7 is closed and opened through the insertionand removal of the spreader 532.

This is channel shaped to hold a label strip. This effects the samelever action as is shown in FIGURE 3 with respect to the closedcondition of the binder. With respect to the opened position, the binderof FIGURES 5 to 7 is held by pinching the rockable members with thefingers. If desired, additional clips or locks (shown in dotted lineform at S44 of FIGURE 7) may be used to hold the rockable members in theprong opening position. The spreader 532 is composed of a transparentplastic channel part 532:1 with its ends overlaying the label strip532b, as shown.

FIGURES 8 and 9 show still another modication of the construction ofFIGURE 3. Parts corresponding to those of FIGURE 3 are given likereference numerals with 600 added. In this form, the member 630 whichjoins the rockable members 626 and 628 is -in two-part form, one pantbeing the headed part 630a which is formed with a cylindrical head alongits length as shown. The other part, 63017, is a cooperating socket partwhich is received over the head part 63051 and forms a rocking joint. Inthe closed condition of the prongs 624, shown in FIGURE 8, the flexedspring spreader 632 urges the rockable members 626 and 628 inprong-closing direction and rocks the par-ts of the prong 624 closedwith the member 630 serving as a fulcrum in the same lever action as isabove described with reference to FIGURE 3. To open the prongs 624, thespreader 632 is withdrawn as above described and the free ends of therockable members 626 land 628 are pinched together to swing the joint ofconnecting member 630 as shown in FIGURE 9, thereby opening the prongs624 for the insertion or removal of the sheets.

In the construction of FIGURE 8, the prong portions 624e and 624b areformed at their ends in concave and convex nesting sections as shown.These serve to key the prong parts together, when closed, to secure thepages more eifectively. The nesting portions are constant section alongthe length of the unit, and `hence can be extended as hereafterdescribed.

FIGURE 11 is a View like FIGURE 8 showing a binder similar to that ofFIGURE 8 but for manufacture from `sheet metal. Parts corresponding tothose in the unit of FIGURE 8 are indicated by like reference numeralswith 1000 added. In the unit of FIGURE 11, the top rockable member 1626is formed integrally with the top portion of the member 1630, as well aswith the top part 1624a of the prong 1624. The top portion of member1630 is bent to dene a cylindrical surface at 163011 to form the innermember of the ball joint. Similarly, the bottom rockable member isformed integrally with the bottom portion 1630b of the member 1630, andwith the bottom portion 1624b of the prong 1624. A socket to receive thecylindrical conformation 1630a of the member 1630 is formed by alternateclock'wise and counterclockwise mating curved portions 16300 and 1630dof the portion 1630b. This construction is shown in side elevationalview in FIGURE 12.

All of the foregoing binder constructions are characterized by the useof relatively rigid prongs which are not flexed for the removal of thesheets. This serves to simplify the construction and in addition servesto hold the sheets in place in firm and unyielding fashion. Moreover, inall of the binder constructions here shown, a pair of relatively rigidrockable members are used. These serve to provide a rm backingconstruction that protects the sheets bound. In addition, they coactwith the spreader used in the respective constructions to form a rigidbackbone or back part which serves to carry an appropriate label ortitle and in addition contributes to the provision of a firm and rigidstructure. This back part is also adapted to lay flat in the position ofFIGURE 2 to rest on a table or other surface with the pages spread outfor convenient reading or other use without the necessity of holding anyof the pages down.

It will be further observed that all of the constructions here shownutilize yan intermediate fulcrum member 30, 430, 530, 630, etc., whichis tensioned tin the closed position of the binder. This member in everyform shown permits rock-able of the rocking members in relation to` eachother, so that the spreader-by spreading the free ends of the rockablemembers-tilts the rockable members about the fulcrum member to urge theprongs to closed position. Thus the roclcable members and the slidemember coact with the fulcrum member to form -a positively closed binderwith the spreader in place. With the spreader removed, this restraintand the laccompanying lever action does not take place and the rockablemembers are free to tilt to the prong-opening position. Sheets can thenbe readily removed or inserted and the spreader replaced to restore theinitially complete and rigid construction.

The forms of the invention shown in FIGURES 1 4, 5 7, and 8-9 have theadvantage of being suitable for construction from plastic materials,especially styrene vinyl, butyrate and polyethylene plastics. Moreover,as above specifically discussed wlith respect to the form of FIGURES 14, the conformations are such las to lend themselves to construction byplastic extrusion techniques. This is highly desirable as it permitsrelatively inexpensive manufacture with a very limited amount ofmachining. In addition, it is possible to form a binder like those ofFIGURES 1-4 and 5-7 by extrusion of these shapes with the prong-formingportions in the form of a partially or wholly spread out continuoussection followed by movement of the soft extrusion Ialong fixed camelements serving to bend the soft prong-forming portion to the finaldesired closed prong shapes. last technique is particularly suitable formanufacture of units with nesting prongs suoh as are shown in FIG- URE8.

In FIGURES 3, 4, 5, `and 7, the fulcrum members and 530 are shown invarious positions of flexure and lack of flexure. The actualconformations assumed by these members under specific conditions dependupon the specific material use for thern, their dimensions (especiallythickness), and the extent of the tension and compression lapplied tothem. It will be understood that the specific conforrnlations shown `areillustrative only land the respective fulcrum members will serve theirpurpose successfully if they are capable of withstanding the tensioncreated by the action of the slide or spreader member, and aresufficiently flexible to permit the rockable members to rock -inrelation to each other at all positions of roclcable member movement.Moreover, if desired, the fulcrum members may be made more flexible bypunching or otherwise placing holes in them, such holes serving toincrease the flexibility of these members to the desired extent, or theymay be made of more flexible material than the remainder of the binding.

While the rocleable members and the prongs are here described asrelatively rigid this term is of necessity used in a relative sense. Aconsiderable degree of flexibility This may be provided in these partswithout impatiring the operation of the binder. The yimportant point isthat these parts do not flex under normal binder use and may accordinglybe made as rigid yas desired without prejudice to the ease of insertionand removal of the sheets.

The rockable members described above rock relative to each other yandform a complementary pair. It will be understood that it is this rockingmovement of the members in relation to each other and not the 'absolutemovement of either alone that is necessary tand `is referred to in theclaims.

If desired, the spreaders, such as spreader 632, FIG- URE 8, may be oftransparent plastic of convex shape with la label on the inside face ofthe same. The spreader then serves to enlarge the lettering on thelabel.

The term hook moment is used herein to designate the prong-closingmoment imparted to the rigid prongs, which is analogous to the moment ona lifting hook. It will be noted that the spreader urges the rockablemembers apart and acts against the thin flexible membrane or othermember that holds the rookable members against spreading intermedi-atetheir edges. Each rockable member is thus subjected to a force coupletending to rook the same in prong-closing direction and is resisted bythe force exerted by the prongs. As in a hook, this force gives nise toa varying bending moment in the prongs.

While I have shown and described specific embodiments of the presentinvention, it will of course be understood that numerous modificationsand alternative constructions may be employed without departing from thetrue spirit and scope thereof. In particular, other forms of relativelyrigid rockable members may be provided with any appropriate number ofsuitable relatively rigid prongs, joined by other forms of fulcrummembers, and provided with other suitable spreading elements at theirfree ends to define the binder. It will, of course, be understood thatthe lappended claims are intended to cover lall such modifications andalternative constructions as fall within their spirit and scope.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A two-part unit for sheets having perforations adjacent one edge, theunit compnising a rst part in the form of an elongated member defining apair of elongated complementary rockable members each having spacedlongitudinal edges, a thin flexible membrane joining said membersintermediate the edges, respectively, and rigid mating prongs extendingin pairs from one edge o-f one rockable member and from thecorresponding edge of the other rockable member, said prongs beingadapted to pass through the perforations of the sheets; and a secondpart in the form of a slide member having overhanging faces and adaptedalternately to slide between or to slide over said rockable membersadjacent the other edges thereof, the slide serving when between therockable members to spread the rookable members, tension the membrane,and close the prongs, and when over the rockable members to draw therockable members together at their edges opposite the prongs, collapsethe membrane, and open the prongs.

2. A two-part blinding unit for sheets having perforations adjacent oneedge and suitable for manufacture by extrusion processes, the unitcomprising a first part in the form of an elongated member defining apair of elongated complementary rockable members each having spacedlongitudinal edges, a thin flexible membnane joining said membersintermediate the edges, respectively, `and rigid interrupted prongsextending betwee-n one edge of one rockable member and the corresponding'edge of the other rockable member, said prongs being 'adapted to passthrough the perforations of the sheets, said rst part being of uniformcross sectional conformation throughout its length with the exception ofthe prongs and the prongs being of uniform cross sectional conformation,whereby the first part may be made by extrusion methods and the prongsformed by cutting operations; and a second part in the form of a slidemember of uniform cross section throughout its length, havingoverhanging faces, and adapted alternatively to slide between or toslide over said rockable members `adjacent the other edges thereof, theslide serving when between the rockable members to spread the rockablemembers at their edges opposite the prongs, tension the membrane, andclose the prongs, and when over the rockable members to draw the sameedges of the rockable members together, ex the membrane, and open theprongs.

3. A binding unit suitable for manufacture by a plastic extrusionprocess and suitable for holding a plurality of sheets havingperforations adjacent one edge, said unit comprising a lpair ofelongated relatively thick and rigid complementary plastic rockablemembers each having spaced longitudinal edges; rigid plastic prongs onat least one rockable member extending between one edge of one memberand the corresponding edge of the other member to form rings to holdsaid sheets by passing through said perforations, said members havingcomplementary ways adjacent the opposite edges thereof; a relativelythin fiexible plastic membrane joining said members intermediate theedges of said members, said membrane being sufiiciently iiexible tonormally permit said rings to open; said members, said rings and saidmembrane being formed of a continuous plastic extrusion cut to form theunit and rings whereby said members, said rings and said membrane areunitary; and a spreader receivable in said ways when said rings areclosed by urging said other members apart to tension said membrane andhold said members in the position at which said rings are closed.

4. A binding unit for sheets having perforations adjacent one edge, theunit comprising: a pair of elongated complementary rigid rockablemembers each having spaced longitudinal edges; rigid prongs on at leastone rockable member extending between one edge of one rockable memberand the corresponding edge of the other rockable member, said prongsbeing adapted to pass through the perforations of the sheets and inclosed position defining a hook that resists closing movement of saidone edge; means joining said members intermediate their respectiveedges, said means permitting relatively free rocking movement of themembers to move the prongs from prong closed to prong opened positionand holding said members intermediate their edges from spacing movement;and a slidable spreading located between said last means and the otheredges of the rockable members, respectively, said last means in oneposition bearing in column action against the rockable members to spreadthe same in prong-closing movement, tension said means, and close theprongs; said spreader also having parts to engage the rockable membersin the prong opened position to hold the same against prong-closingmovement.

5. A binding unit for sheets having perforations at one edge, the unitcomprising: a pair of elongated complementary rigid rockable memberseach having spaced longitudinal edges; means defining rigid interruptedprongs on at least one rockable member extending between one edge of onerockable member and the corresponding edge of the other rockable member,said prongs being adapted to pass through the perforations of thesheets; and in closed position defining a hook that resists closingmovement of said one edge; a flexible membrane joining the membersintermediate their edges; a spreader adapted to t between the rockingmembers near the other edges thereof to bear against the inside facesthereof in column action to spread the same, tension the membrane, andclose the prongs, said spreader being further adapted in alternateposition to engage the outside faces of the rockable members near saidother edges to draw the rockable members together, ex the membrane, andopen the prongs.

6. A binding unit for sheets having perforations at one edge, the unitcomprising: a pair of elongated complementary rigid rockable memberseach having spaced longitudinal edges, the one set of complementaryedges of said rockable members defining inner and outer ways on theirinner and outer surfaces respectively; means defining rigid interruptedprongs on at least one rockable member extending between the other edgeof one rockable member and the other edge of the other rockable member,said prongs being adapted to pass through the perforations of the sheetsand in closed position defining a hook that resists closing movement ofsaid one edge; a thin flexible membrane joining the rockable membersintermediate their edges; a slide defining inner and outer Wayscomplementary to and slidable upon the outer and inner ways,respectively, of the rockable members, the slide serving with its outerways bearing on the inside ways of the rockable members to spread therockable members, tension the membrane, and close the prongs, the slidebeing further adapted with its inner ways on the outer ways of therockable members to draw the rockable members together at their edgesopposite the prongs, ex the membrane, and open the prongs.

7. An extrudable one piece binder part adapted to receive a plurality ofsheets with holes on one edge, said binder part being of homogenousmaterial and defining a pair of elongated spaced relatively thick rigidcomplementary members each having spaced parallel edges, a relativelythin flexible tension-resisting web joined integrally to said membersintermediate said edges and extending substantially the length of saidmembers to hold the same in longitudinal alignment, said binder partfurther defining relatively thick prongs integral with at least one ofsaid members and forming C-shaped interrupted hook-like sheet-receivingstructures etxending between one edge of one of said members and thecorresponding edge of the other of said members to open when the membersare rocked in one direction relative to each other and to resistmovement of said members when rocked beyond prong-engaging position inthe opposite direction, said members being adapted to receive a spreadermember near the other edges of said members to spread the members inprong-closing direction, tension the Web, and hold the binder part inclosed sheet-retaining position.

References Cited in the file of this patent UNITED STATES PATENTS2,425,205 Raynolds Aug. 5, 1947 FOREIGN PATENTS 7,081 Great Britain Mar.21, 1910

